Exhaust system for a motorcycle



FIG. 1 is a right view of an exhaust system for a motorcycle, showing my new design;

FIG. 2 is an enlarged right view thereof;

FIG. 3 is an enlarged top view thereof;

FIG. 4 is an enlarged front view thereof;

FIG. 5 is an enlarged left view thereof;

FIG. 6 is an enlarged rear view thereof; and,

FIG. 7 is an enlarged bottom view thereof.

The broken line showing of environment is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for an exhaust system for a motorcycle, as shown and described. 